Really Good Emails - A large collection of good product email design.
pickSaaS - Hundreds of SaaS products, analyzed.
Good Sales Emails - Best sales emails from great companies
Inside SaaS Sales - 1000+ sales emails and voicemails from top SaaS companies
Great Email Copy - A dose of emails from around the web.
SaaS 1000 - Free exportable list of the fastest growing SaaS companies